I have thought about it matt but i think there is some kind of problem in the wiring.Obd website tells you the P0402 code could be triggered by a faulty egr and could be the dpfe sensor which i think is something to do with the wiring. i have noticed on this website that some get the cheater and later still get the egr fault code which could be related to this dpse fault rather than a faulty cheater which you would think of first rather than some other kind of fault i will do some investigating over the weekend.
Checked a couple of you tube vids and you see them testing voltage on the pins .they say if you get the p0401 code do not change the egr valve although mine is P0402 i think i am having the same problem its something to do with the flow maybe blocked or a fault in the actual connection plug need more time to investigate just got code reader on and read then cleared code without checking all this voltage stuff which i think you can do with the code readers never knew too much at the time just assumed faulty egr change that and problem solved
